Czech and Slovak are two Slavic, mutually intelligible languages. Their relationship could be described as a semicommunication (Haugen, 1966) or a receptive bilingualism.
The contact between them is still very strong, since a high number of Slovaks reside in Czechia for many purposes (e.g. work, study). Despite the close relationship between languages in question, cases of Slovaks accommodating to Czech have been reported (Sloboda, 2005).
The present paper deals with this issue mainly from a psycholinguistic point of view. It summarizes the results of a lexical decision task, method, that has been not employed in the investigation of the Czech and Slovak contact so far.
The task was focused on processing and producing, respectively, of Slovak and Czech words. The aim was to find out whether and under what conditions a long-term stay in the Czech speaking environment leads to the attrition of Slovak (L1) and to what extend Czech words are mastered and activated in a mental lexicon in native speakers of Slovak.
The emphasis was put on a mental lexicon because it is "one of the most vulnerable areas affected by language attrition" (Cherciov, 2012). L1 attrition is generally defined as "the non pathological loss of a language in, usually, bilingual subjects" (Köpke, 2004).
Although in psycholinguistics a lexical decision task is broadly used experimental method, in L1 attrition research it has received little attention (Schmid, Köpke, 2009). Additionally, L1 attrition research concerns traditionally languages which have not as so tight connections as Czech and Slovak.
Thus, the present study has a potential to enrich the field. Two groups of Slovak native speakers took part in the task.
One group consisted of Slovaks living in Slovakia (control group; n = 50) and second group of Slovaks living in Czechia (n = 66). The latter group was subdivided according to the amount of use of Czech and Slovak.
Another control group comprised native speakers of Czech living in Czechia (n = 49). This group performed only tasks orientated to the processing of Czech.
Word stimuli were categorized into two groups based on a similarity between equivalents (identical cognates vs. non-cognates). The results have shown that as far as Slovaks are concerned Slovak stimuli were processed faster than Czech stimuli in all groups of speakers, with the exception of words which have same form in both languages.
Completely different Czech words (with respect to their equivalent) were responded the most slowly. Signs of L1 attrition have been observed.
Explanations of results, the influence of other factors (e.g. the length of residence in Czechia) on the data and consequences for L1 attrition research area are discussed.